A method of simulating ink-particle flight for industrial, continuous inkjet printers (CIJPs) was developed to clarify the factors that influence print distortion. Print distortion is produced by aerodynamic and electric interference between the ink-particles flying from the nozzle onto the print target. The necessary functions to do this, such as the calculation of electrostatic force in the electric field between the electrodes, Coulomb's force from other charged ink-particles, and the drag force in the inkjet stream for many flying ink-particles were added to a Lagrangian method in the software to analyze the fluid dynamics that was used in the simulations. The trajectories of the ink particles flying from the nozzle onto the print target and the air flow caused by them were simultaneously calculated in the simulations. The results from simulations for the velocities and trajectories of the flying ink particles were compared with the experimental ones obtained with a high-speed camera. These simulation results were in good agreement with the experimental ones, and the developed simulation helps to clarify the factors that influence print distortion and to create algorithms that decrease it.